1. Field of the Invention
The present invention relates generally to the field of laboratory equipment and, more specifically, to apparatus for distilling or separating liquids.
2. Discussion of the Related Art
A device known in the art as a "kugelrohr apparatus" is used to distill or separate a liquid sample in preparation for analytical testing. One such apparatus, which has been commercially available from Aldrich Chemical Company, Inc. of Milwaukee, Wis. for many years, consists of several major components: an air oven; a number of round bottom flasks which are connected together in a series; a drive unit; a vacuum source; and an ice bath. A liquid sample is placed in one of the flasks which, in turn, is placed inside the air oven with the neck (outlet) of the flask extending through the sidewall of the oven and connecting with the next flask in the series. The outlet of the last flask of the series is coupled to the drive unit and the vacuum source. The ice bath is placed beneath the flasks between the oven and drive unit. As the oven heats the sample, the drive unit rotates the flasks back and forth in an oscillating motion to prevent violent boiling and uneven heating. The sample (or components thereof) evaporates and is drawn from one flask to the next in succession while being cooled by the ice bath. The vapor condenses, becoming a distillate which may then be collected for analysis.
Conventional kugelrohr apparati suffer from numerous safety and performance deficiencies. For example, in the Aldrich Chemical device referenced above, the air oven is constructed from an aluminum coffee pot having a removable glass top. The bottom of the coffee pot is fitted with a threaded, ungrounded (lamp type) electrical receptacle. Thus, when the receptacle is empty while the power is on, line voltage is present in the receptacle and represents a shock hazard.
An ungrounded heating element is usually screwed into the receptacle. Because the heating element is exposed within the interior of the coffee pot and operates at a high temperature (i.e., the element is red hot), there is a substantial burn hazard to personnel who must reach into the pot to insert or remove flasks. The aluminum sidewalls of the coffee pot, as well as its glass cover, also represent burn hazards.
Another disadvantage of the modified coffee pot oven arises from the fact that the heating element and electrical receptacle are unsealed. Thus, in the event that a flask should break and release liquid into the interior of the oven, the heating element will likely be ruined, liquid may be ignited or enter the receptacle and cause a short, and the entire oven will probably be damaged beyond repair.
Also, the drive unit of a conventional kugelrohr apparatus suffers from several disadvantages. Typically, such drive units use 1940's-vintage windshield wiper motors to provide back and forth rotation of the connected flasks. Such motors are disadvantageous because they are no longer in wide use and cannot easily be replaced or repaired. Further, such motors require compressed air or vacuum as a power source, neither of which may be readily available in many instances. Lastly, the conventional drive unit was not free-standing, but instead required an external support such as ring stand and clamp.